The Mizar article:

Gauges

by
Czeslaw Bylinski

Received January 22, 1999

Copyright (c) 1999 Association of Mizar Users

MML identifier: JORDAN8
[ MML identifier index ]


environ

 vocabulary FINSEQ_1, MATRIX_1, RELAT_1, FINSEQ_4, BOOLE, FUNCT_1, GOBOARD1,
      ABSVALUE, ARYTM_1, RFINSEQ, PRE_TOPC, EUCLID, GOBOARD5, TOPREAL1,
      GOBOARD2, TREES_1, MCART_1, SEQM_3, COMPTS_1, SPPOL_1, PSCOMP_1, ARYTM_3,
      GROUP_1, INCSP_1, JORDAN8;
 notation TARSKI, XBOOLE_0, ZFMISC_1, XREAL_0, REAL_1, NAT_1, STRUCT_0,
      BINARITH, ABSVALUE, RELAT_1, FUNCT_1, CARD_4, FINSEQ_1, FINSEQ_4,
      RFINSEQ, MATRIX_1, PRE_TOPC, COMPTS_1, EUCLID, TOPREAL1, GOBOARD1,
      GOBOARD2, SPPOL_1, PSCOMP_1, GOBOARD5;
 constructors REAL_1, ABSVALUE, FINSEQ_4, CARD_4, RFINSEQ, SEQM_3, BINARITH,
      COMPTS_1, GOBOARD2, SPPOL_1, PSCOMP_1, GOBOARD5;
 clusters STRUCT_0, RELAT_1, RELSET_1, EUCLID, GOBOARD2, FINSEQ_5, SPRECT_1,
      NAT_1, MEMBERED;
 requirements REAL, NUMERALS, BOOLE, SUBSET, ARITHM;
 definitions GOBOARD1, GOBOARD5, TOPREAL1, XBOOLE_0;
 theorems ZFMISC_1, NAT_1, FINSEQ_1, MATRIX_1, GOBOARD1, FINSEQ_4, EUCLID,
      FINSEQ_3, AXIOMS, REAL_1, REAL_2, HEINE, JORDAN3, SQUARE_1, PSCOMP_1,
      SPRECT_1, FINSEQ_5, GOBOARD7, TOPREAL1, GOBOARD5, SPRECT_2, ABSVALUE,
      GROUP_5, GOBOARD9, UNIFORM1, SUBSET_1, GOBRD11, GOBOARD2, SPRECT_3,
      JORDAN5D, SCMFSA_7, RELAT_1, XBOOLE_0, XBOOLE_1, XCMPLX_1;
 schemes MATRIX_1;

begin

reserve i,i1,i2,i',i1',j,j1,j2,j',j1',k,l,m,n for Nat;
reserve r,s,r',s' for Real;

reserve D for set,
        f for FinSequence of D,
        G for Matrix of D;

theorem
    len f >= 2 implies f|2 = <*f/.1,f/.2*>
proof assume
A1: len f >= 2;
then A2: len(f|2) = 2 by TOPREAL1:3;
  set d1 = f/.1, d2 = f/.2;
     now
A3:  rng f c= D by FINSEQ_1:def 4;
    assume D is empty;
     then rng f = {} by A3,XBOOLE_1:3;
     then f = {} by RELAT_1:64;
     then len f = 0 by FINSEQ_1:25;
    hence contradiction by A1;
   end;
   then reconsider D as non empty set;
   reconsider f as FinSequence of D;
     1 in dom(f|2) by A2,FINSEQ_3:27;
then A4:  d1 = (f|2)/.1 by TOPREAL1:1
       .= (f|2).1 by A2,FINSEQ_4:24;
     2 in dom(f|2) by A2,FINSEQ_3:27;
   then d2 = (f|2)/.2 by TOPREAL1:1
          .= (f|2).2 by A2,FINSEQ_4:24;
  hence thesis by A2,A4,FINSEQ_1:61;
end;

theorem
    k+1 <= len f implies f|(k+1) = (f|k)^<*f/.(k+1)*>
proof assume
A1:  k+1 <= len f;
   1 <= k+1 by NAT_1:37;
then A2: k+1 in dom f by A1,FINSEQ_3:27;
   f|k = f|Seg k by TOPREAL1:def 1;
 then f|Seg(k+1) = (f|k)^<*f.(k+1)*> by A2,FINSEQ_5:11;
 hence f|(k+1) = (f|k)^<*f.(k+1)*> by TOPREAL1:def 1
              .= (f|k)^<*f/.(k+1)*> by A2,FINSEQ_4:def 4;
end;

theorem
    <*>D is_sequence_on G
proof set f = <*>D;
 thus (for n st n in dom f ex i,j st [i,j] in Indices G & f/.n = G*(i,j)) &
 for n st n in dom f & n+1 in dom f holds
    for m,k,i,j st [m,k] in Indices G & [i,j] in Indices G &
                   f/.n = G*(m,k) & f/.(n+1) = G*(i,j)
     holds abs(m-i)+abs(k-j) = 1;
end;

canceled;

theorem
   for D being non empty set, f being FinSequence of D, G being Matrix of D
   st f is_sequence_on G
  holds f/^m is_sequence_on G
proof let D be non empty set, f be FinSequence of D, G be Matrix of D such that
A1: for n st n in dom f ex i,j st [i,j] in Indices G & f/.n = G*(i,j) and
A2: for n st n in dom f & n+1 in dom f
     for m,k,i,j
      st [m,k] in Indices G & [i,j] in
Indices G & f/.n=G*(m,k) & f/.(n+1)=G*(i,j)
     holds abs(m-i)+abs(k-j) = 1;
 set g = f/^m;
 hereby
  let n; assume
A3:  n in dom g;
  then n+m in dom f by FINSEQ_5:29;
  then consider i,j such that
A4:  [i,j] in Indices G and
A5:  f/.(n+m) = G*(i,j) by A1;
  take i,j;
  thus [i,j] in Indices G by A4;
  thus g/.n = G*(i,j) by A3,A5,FINSEQ_5:30;
 end;
 let n such that
A6:  n in dom g and
A7:  n+1 in dom g;
 let i1,j1,i2,j2 such that
A8:  [i1,j1] in Indices G & [i2,j2] in Indices G and
A9:  g/.n = G*(i1,j1) & g/.(n+1) = G*(i2,j2);
A10:  n+m in dom f by A6,FINSEQ_5:29;
A11:  n+1+m = n+m+1 by XCMPLX_1:1;
then A12:  n+m+1 in dom f by A7,FINSEQ_5:29;
   f/.(n+m) = g/.n & f/.(n+m+1) = g/.(n+1) by A6,A7,A11,FINSEQ_5:30;
 hence abs(i1-i2)+abs(j1-j2) = 1 by A2,A8,A9,A10,A12;
end;

theorem Th6:
  1 <= k & k+1 <= len f & f is_sequence_on G
   implies ex i1,j1,i2,j2 being Nat st
     [i1,j1] in Indices G & f/.k = G*(i1,j1) &
     [i2,j2] in Indices G & f/.(k+1) = G*(i2,j2) &
     (i1 = i2 & j1+1 = j2 or i1+1 = i2 & j1 = j2 or
      i1 = i2+1 & j1 = j2 or i1 = i2 & j1 = j2+1)
proof
 assume that
A1:  1 <= k & k+1 <= len f and
A2:  f is_sequence_on G;
      k <= k+1 by NAT_1:29;
    then k <= len f by A1,AXIOMS:22;
then A3:  k in dom f by A1,FINSEQ_3:27;
    then consider i1,j1 being Nat such that
A4:  [i1,j1] in Indices G & f/.k = G*(i1,j1) by A2,GOBOARD1:def 11;
      k+1 >= 1 by NAT_1:29;
then A5:  k+1 in dom f by A1,FINSEQ_3:27;
    then consider i2,j2 being Nat such that
A6:  [i2,j2] in Indices G & f/.(k+1) = G*(i2,j2) by A2,GOBOARD1:def 11;
A7:  abs(i1-i2)+abs(j1-j2) = 1 by A2,A3,A4,A5,A6,GOBOARD1:def 11;
      now per cases by A7,GOBOARD1:2;
     case that
A8:  abs(i1-i2) = 1 and
A9:  j1 = j2;
A10:   -(i1-i2) = i2-i1 by XCMPLX_1:143;
        i1-i2 >= 0 or i1-i2 < 0;
      then i1-i2 = 1 or -(i1-i2) = 1 by A8,ABSVALUE:def 1;
     hence i1 = i2+1 or i1+1 = i2 by A10,XCMPLX_1:27;
     thus j1 = j2 by A9;
     case that
A11:  i1 = i2 and
A12:  abs(j1-j2) = 1;
A13:   -(j1-j2) = j2-j1 by XCMPLX_1:143;
        j1-j2 >= 0 or j1-j2 < 0;
      then j1-j2 = 1 or -(j1-j2) = 1 by A12,ABSVALUE:def 1;
     hence j1 = j2+1 or j1+1 = j2 by A13,XCMPLX_1:27;
     thus i1 = i2 by A11;
    end;
  hence thesis by A4,A6;
end;

reserve G for Go-board,
        p for Point of TOP-REAL 2;

theorem
   for f being non empty FinSequence of TOP-REAL 2 st f is_sequence_on G
   holds f is standard special
proof let f be non empty FinSequence of TOP-REAL 2 such that
A1:  f is_sequence_on G;
 thus f is_sequence_on GoB f
  proof set F = GoB f;
   thus for n st n in dom f
     ex i,j st [i,j] in Indices GoB f & f/.n = (GoB f)*
(i,j) by GOBOARD2:25;
   let n such that
A2:   n in dom f & n+1 in dom f;
   let m,k,i,j such that
A3:  [m,k] in Indices GoB f and
A4:  [i,j] in Indices GoB f and
A5:  f/.n = (GoB f)*(m,k) and
A6:  f/.(n+1) = (GoB f)*(i,j);
A7:  1 <= m & m <= len F & 1 <= k & k <= width F by A3,GOBOARD5:1;
A8:  1 <= i & i <= len F & 1 <= j & j <= width F by A4,GOBOARD5:1;
then A9:  F*(i,j)`1 = F*(i,1)`1 & F*(i,k)`1 = F*(i,1)`1 by A7,GOBOARD5:3;
A10:  F*(i,j)`2 = F*(1,j)`2 & F*(m,j)`2 = F*(1,j)`2 by A7,A8,GOBOARD5:2;
     1 <= n & n+1 <= len f by A2,FINSEQ_3:27;
   then consider i1,j1,i2,j2 such that
A11:  [i1,j1] in Indices G and
A12:  f/.n = G*(i1,j1) and
A13:  [i2,j2] in Indices G and
A14:  f/.(n+1) = G*(i2,j2) and
A15:  i1 = i2 & j1+1 = j2 or i1+1 = i2 & j1 = j2 or
      i1 = i2+1 & j1 = j2 or i1 = i2 & j1 = j2+1 by A1,Th6;
A16:  1 <= i1 & i1 <= len G & 1 <= j1 & j1 <= width G by A11,GOBOARD5:1;
A17:  1 <= i2 & i2 <= len G & 1 <= j2 & j2 <= width G by A13,GOBOARD5:1;
then A18:  G*(i1,j1)`1 = G*(i1,1)`1 & G*(i2,j2)`1 = G*(i2,1)`1
        by A16,GOBOARD5:3;
A19:  G*(i1,j1)`2 = G*(1,j1)`2 & G*(i2,j1)`2 = G*(1,j1)`2
        by A16,A17,GOBOARD5:2;
A20:  k+1 >= 1 & j+1 >= 1 & m+1 >= 1 & i+1 >= 1 by NAT_1:37;
A21:  k+1 > k & j+1 > j & m+1 > m & i+1 > i by NAT_1:38;
   per cases by A15;
   suppose
A22:   i1 = i2 & j1+1 = j2;
      now assume m <> i;
       then m < i or m > i by REAL_1:def 5;
      hence contradiction by A5,A6,A7,A8,A9,A12,A14,A18,A22,GOBOARD5:4;
    end;
    then m-i = 0 by XCMPLX_1:14;
then A23: abs(m-i) = 0 by ABSVALUE:7;
      now assume j <= k;
then A24:     F*(i,j)`2 <= F*(m,k)`2 by A7,A8,A10,SPRECT_3:24;
       j1 < j2 by A22,NAT_1:38;
     hence contradiction by A5,A6,A12,A14,A16,A17,A19,A24,GOBOARD5:5;
    end;
then A25:   k+1 <= j by NAT_1:38;
      now assume
A26:    k+1 < j;
then A27:    k+1 < width F by A8,AXIOMS:22;
     then consider l,i' such that
A28:    l in dom f and
A29:    [i',k+1] in Indices F and
A30:    f/.l = F*(i',k+1) by A20,JORDAN5D:10;
      1 <= i' & i' <= len F by A29,GOBOARD5:1;
then A31:    F*(i',k+1)`2 = F*(1,k+1)`2 & F*(m,k+1)`2 = F*(1,k+1)`2
        by A7,A20,A27,GOBOARD5:2;
     consider i1',j1' such that
A32:    [i1',j1'] in Indices G and
A33:    f/.l = G*(i1',j1') by A1,A28,GOBOARD1:def 11;
A34:    1 <= i1' & i1' <= len G & 1 <= j1' & j1' <= width G by A32,GOBOARD5:1;
then A35:    G*(i1',j1')`2 = G*(1,j1')`2 & G*(i1',j1)`2 = G*(1,j1)`2
        by A16,GOBOARD5:2;
A36:    G*(i2,j2)`2 = G*(1,j2)`2 & G*(i1',j2)`2 = G*(1,j2)`2
        by A17,A34,GOBOARD5:2;
A37:  now assume j1 >= j1';
then G*(i1',j1')`2 <= G*(i1,j1)`2 by A16,A19,A34,A35,SPRECT_3:24;
       hence contradiction by A5,A7,A12,A21,A27,A30,A31,A33,GOBOARD5:5;
      end;
        now assume j2 <= j1';
then G*(i2,j2)`2 <= G*(i1',j1')`2 by A17,A34,A36,SPRECT_3:24;
       hence contradiction by A6,A7,A8,A10,A14,A20,A26,A30,A31,A33,GOBOARD5:5;
      end;
     hence contradiction by A22,A37,NAT_1:38;
    end;
    then k+1 = j by A25,AXIOMS:21;
    then j-k = 1 by XCMPLX_1:26;
    then abs(j-k) = 1 by ABSVALUE:def 1;
    hence thesis by A23,UNIFORM1:13;
   suppose
A38:   i1+1 = i2 & j1 = j2;
      now assume k <> j;
       then k < j or k > j by REAL_1:def 5;
      hence contradiction by A5,A6,A7,A8,A10,A12,A14,A19,A38,GOBOARD5:5;
    end;
    then k-j = 0 by XCMPLX_1:14;
then A39:   abs(k-j) = 0 by ABSVALUE:7;
      now assume i <= m;
then A40:     F*(i,j)`1 <= F*(m,k)`1 by A7,A8,A9,SPRECT_3:25;
       i1 < i2 by A38,NAT_1:38;
     hence contradiction by A5,A6,A12,A14,A16,A17,A38,A40,GOBOARD5:4;
    end;
then A41:   m+1 <= i by NAT_1:38;
      now assume
A42:    m+1 < i;
then A43:    m+1 < len F by A8,AXIOMS:22;
     then consider l,j' such that
A44:    l in dom f and
A45:    [m+1,j'] in Indices F and
A46:    f/.l = F*(m+1,j') by A20,JORDAN5D:9;
      1 <= j' & j' <= width F by A45,GOBOARD5:1;
then A47:    F*(m+1,j')`1 = F*(m+1,1)`1 & F*(m+1,k)`1 = F*(m+1,1)`1
        by A7,A20,A43,GOBOARD5:3;
     consider i1',j1' such that
A48:    [i1',j1'] in Indices G and
A49:    f/.l = G*(i1',j1') by A1,A44,GOBOARD1:def 11;
A50:    1 <= i1' & i1' <= len G & 1 <= j1' & j1' <= width G by A48,GOBOARD5:1;
then A51:    G*(i1',j1')`1 = G*(i1',1)`1 & G*(i1,j1')`1 = G*(i1,1)`1
        by A16,GOBOARD5:3;
A52:    G*(i2,j2)`1 = G*(i2,1)`1 & G*(i2,j1')`1 = G*(i2,1)`1
        by A17,A50,GOBOARD5:3;
A53:  now assume i1 >= i1';
then G*(i1',j1')`1 <= G*(i1,j1)`1 by A16,A18,A50,A51,SPRECT_3:25;
       hence contradiction by A5,A7,A12,A21,A43,A46,A47,A49,GOBOARD5:4;
      end;
        now assume i2 <= i1';
then G*(i2,j2)`1 <= G*(i1',j1')`1 by A17,A50,A52,SPRECT_3:25;
       hence contradiction by A6,A7,A8,A9,A14,A20,A42,A46,A47,A49,GOBOARD5:4
;
      end;
     hence contradiction by A38,A53,NAT_1:38;
    end;
    then m+1 = i by A41,AXIOMS:21;
    then i-m = 1 by XCMPLX_1:26;
    then abs(i-m) = 1 by ABSVALUE:def 1;
    hence thesis by A39,UNIFORM1:13;
   suppose
A54:   i1 = i2+1 & j1 = j2;
      now assume k <> j;
       then k < j or k > j by REAL_1:def 5;
      hence contradiction by A5,A6,A7,A8,A10,A12,A14,A19,A54,GOBOARD5:5;
    end;
    then k-j = 0 by XCMPLX_1:14;
then A55:   abs(k-j) = 0 by ABSVALUE:7;
      now assume m <= i;
then A56:     F*(i,j)`1 >= F*(m,k)`1 by A7,A8,A9,SPRECT_3:25;
       i1 > i2 by A54,NAT_1:38;
     hence contradiction by A5,A6,A12,A14,A16,A17,A54,A56,GOBOARD5:4;
    end;
then A57:   i+1 <= m by NAT_1:38;
      now assume
A58:    i+1 < m;
then A59:    i+1 < len F by A7,AXIOMS:22;
     then consider l,j' such that
A60:    l in dom f and
A61:    [i+1,j'] in Indices F and
A62:    f/.l = F*(i+1,j') by A20,JORDAN5D:9;
      1 <= j' & j' <= width F by A61,GOBOARD5:1;
then A63:    F*(i+1,j')`1 = F*(i+1,1)`1 & F*(i+1,j)`1 = F*(i+1,j)`1
        by A20,A59,GOBOARD5:3;
A64:    F*(i+1,k)`1 = F*(i+1,1)`1 & F*(i+1,j)`1 = F*(i+1,1)`1
        by A7,A8,A20,A59,GOBOARD5:3;
     consider i1',j1' such that
A65:    [i1',j1'] in Indices G and
A66:    f/.l = G*(i1',j1') by A1,A60,GOBOARD1:def 11;
A67:    1 <= i1' & i1' <= len G & 1 <= j1' & j1' <= width G by A65,GOBOARD5:1;
then A68:    G*(i1',j1')`1 = G*(i1',1)`1 & G*(i1,j1')`1 = G*(i1,1)`1
        by A16,GOBOARD5:3;
A69:    G*(i2,j2)`1 = G*(i2,1)`1 & G*(i2,j1')`1 = G*(i2,1)`1
        by A17,A67,GOBOARD5:3;
A70:  now assume i2 >= i1';
then G*(i1',j1')`1 <= G*(i2,j2)`1 by A17,A67,A69,SPRECT_3:25;
       hence contradiction by A6,A8,A14,A21,A59,A62,A63,A64,A66,GOBOARD5:4;
      end;
        now assume i1 <= i1';
then G*(i1,j1)`1 <= G*(i1',j1')`1 by A16,A18,A67,A68,SPRECT_3:25;
       hence contradiction by A5,A7,A12,A20,A58,A62,A63,A64,A66,GOBOARD5:4;
      end;
     hence contradiction by A54,A70,NAT_1:38;
    end;
    then i+1 = m by A57,AXIOMS:21;
    then m-i = 1 by XCMPLX_1:26;
    hence thesis by A55,ABSVALUE:def 1;
   suppose
A71:   i1 = i2 & j1 = j2+1;
      now assume m <> i;
       then m < i or m > i by REAL_1:def 5;
      hence contradiction by A5,A6,A7,A8,A9,A12,A14,A18,A71,GOBOARD5:4;
    end;
    then m-i = 0 by XCMPLX_1:14;
then A72:   abs(m-i) = 0 by ABSVALUE:7;
      now assume j >= k;
then A73:     F*(i,j)`2 >= F*(m,k)`2 by A7,A8,A10,SPRECT_3:24;
       j1 > j2 by A71,NAT_1:38;
     hence contradiction by A5,A6,A12,A14,A16,A17,A19,A73,GOBOARD5:5;
    end;
then A74:   j+1 <= k by NAT_1:38;
      now assume
A75:    j+1 < k;
then A76:    j+1 < width F by A7,AXIOMS:22;
     then consider l,i' such that
A77:    l in dom f and
A78:    [i',j+1] in Indices F and
A79:    f/.l = F*(i',j+1) by A20,JORDAN5D:10;
      1 <= i' & i' <= len F by A78,GOBOARD5:1;
then A80:    F*(i',j+1)`2 = F*(1,j+1)`2 & F*(i,j+1)`2 = F*(1,j+1)`2
        by A8,A20,A76,GOBOARD5:2;
A81:    F*(m,j+1)`2 = F*(1,j+1)`2 & F*(i,j+1)`2 = F*(1,j+1)`2
        by A7,A8,A20,A76,GOBOARD5:2;
     consider i1',j1' such that
A82:    [i1',j1'] in Indices G and
A83:    f/.l = G*(i1',j1') by A1,A77,GOBOARD1:def 11;
A84:    1 <= i1' & i1' <= len G & 1 <= j1' & j1' <= width G by A82,GOBOARD5:1;
then A85:    G*(i1',j1')`2 = G*(1,j1')`2 & G*(i1',j1)`2 = G*(1,j1)`2
        by A16,GOBOARD5:2;
A86:    G*(i2,j2)`2 = G*(1,j2)`2 & G*(i1',j2)`2 = G*(1,j2)`2
        by A17,A84,GOBOARD5:2;
A87:  now assume j2 >= j1';
then G*(i1',j1')`2 <= G*(i2,j2)`2 by A17,A84,A86,SPRECT_3:24;
       hence contradiction by A6,A8,A14,A21,A76,A79,A80,A83,GOBOARD5:5;
      end;
        now assume j1 <= j1';
then G*(i1,j1)`2 <= G*(i1',j1')`2 by A16,A19,A84,A85,SPRECT_3:24;
       hence contradiction by A5,A7,A12,A20,A75,A79,A80,A81,A83,GOBOARD5:5;
      end;
     hence contradiction by A71,A87,NAT_1:38;
    end;
    then j+1 = k by A74,AXIOMS:21;
    then k-j = 1 by XCMPLX_1:26;
    hence thesis by A72,ABSVALUE:def 1;
  end;
 thus f is special
  proof let i;
   assume 1 <= i & i+1 <= len f;
   then consider i1,j1,i2,j2 such that
A88:  [i1,j1] in Indices G and
A89: f/.i = G*(i1,j1) and
A90:  [i2,j2] in Indices G and
A91: f/.(i+1) = G*(i2,j2) and
A92:  i1 = i2 & j1+1 = j2 or i1+1 = i2 & j1 = j2 or
      i1 = i2+1 & j1 = j2 or i1 = i2 & j1 = j2+1 by A1,Th6;
    1 <= i1 & i1 <= len G & 1 <= j1 & j1 <= width G &
      1 <= i2 & i2 <= len G & 1 <= j2 & j2 <= width G by A88,A90,GOBOARD5:1;
   then G*(i1,j1)`2 = G*(1,j1)`2 & G*(i2,j1)`2 = G*(1,j1)`2 &
    G*(i1,j2)`2 = G*(1,j2)`2 & G*(i2,j2)`2 = G*(1,j2)`2 &
     G*(i1,j1)`1 = G*(i1,1)`1 & G*(i1,j2)`1 = G*(i1,1)`1 &
      G*(i2,j1)`1 = G*(i2,1)`1 & G*(i2,j2)`1 = G*(i2,1)`1 by GOBOARD5:2,3;
   hence (f/.i)`1 = (f/.(i+1))`1 or (f/.i)`2 = (f/.(i+1))`2
    by A89,A91,A92;
  end;
end;

theorem
   for f being non empty FinSequence of TOP-REAL 2 st
    len f >= 2 & f is_sequence_on G
   holds f is non constant
proof let f be non empty FinSequence of TOP-REAL 2 such that
A1:  len f >= 2 and
A2:  f is_sequence_on G;
   assume
A3:  for n,m st n in dom f & m in dom f holds f.n = f.m;
       1 <= len f by A1,AXIOMS:22;
then A4:  1 in dom f by FINSEQ_3:27;
    then consider i1,j1 such that
A5:   [i1,j1] in Indices G and
A6:   f/.1 = G*(i1,j1) by A2,GOBOARD1:def 11;
A7:  1+1 in dom f by A1,FINSEQ_3:27;
    then consider i2,j2 such that
A8:   [i2,j2] in Indices G and
A9:   f/.2 = G*(i2,j2) by A2,GOBOARD1:def 11;
     f/.1 = f.1 by A4,FINSEQ_4:def 4
         .= f.2 by A3,A4,A7
         .= f/.2 by A7,FINSEQ_4:def 4;
   then i1 = i2 & j1 = j2 by A5,A6,A8,A9,GOBOARD1:21;
   then i1-i2 = 0 & j1-j2 = 0 by XCMPLX_1:14;
then A10:  abs(i1-i2) = 0 & abs(j1-j2) = 0 by ABSVALUE:7;
     abs(i1-i2) + abs(j1-j2) = 1 by A2,A4,A5,A6,A7,A8,A9,GOBOARD1:def 11;
   hence contradiction by A10;
end;

theorem
   for f being non empty FinSequence of TOP-REAL 2
   st f is_sequence_on G &
     (ex i,j st [i,j] in Indices G & p = G*(i,j)) &
     (for i1,j1,i2,j2
      st [i1,j1] in Indices G & [i2,j2] in Indices G &
         f/.len f = G*(i1,j1) & p = G*(i2,j2)
      holds abs(i2-i1)+abs(j2-j1) = 1)
  holds f^<*p*> is_sequence_on G
proof let f be non empty FinSequence of TOP-REAL 2 such that
A1: f is_sequence_on G and
A2: ex i,j st [i,j] in Indices G & p = G*(i,j) and
A3: for i1,j1,i2,j2
      st [i1,j1] in Indices G & [i2,j2] in Indices G &
         f/.len f = G*(i1,j1) & p = G*(i2,j2)
      holds abs(i2-i1)+abs(j2-j1) = 1;
A4: for n st n in dom f & n+1 in dom f holds
 for m,k,i,j st [m,k] in Indices G & [i,j] in Indices G & f/.n=G*(m,k) &
                f/.(n+1)=G*(i,j) holds abs(m-i)+abs(k-j)=1
  by A1,GOBOARD1:def 11;
A5: now let n;
     assume n in dom <*p*> & n+1 in dom <*p*>;
     then 1 <= n & n+1 <= len <*p*> by FINSEQ_3:27;
     then 1+1 <= n+1 & n+1 <= 1 by AXIOMS:24,FINSEQ_1:56;
     hence for m,k,i,j st [m,k] in Indices G & [i,j] in Indices G &
             <*p*>/.n=G*(m,k) & <*p*>/.(n+1)=G*(i,j)
            holds abs(m-i)+abs(k-j)=1 by AXIOMS:22;
    end;
    now let m,k,i,j such that
A6:  [m,k] in Indices G & [i,j] in Indices G & f/.len f=G*(m,k) &
      <*p*>/.1=G*(i,j) and len f in dom f & 1 in dom <*p*>;
      <*p*>/.1 = p by FINSEQ_4:25;
    then abs(i-m)+abs(j-k)=1 by A3,A6;
    hence 1 = abs(m-i)+abs(j-k) by UNIFORM1:13
           .= abs(m-i)+abs(k-j) by UNIFORM1:13;
  end;
then A7:  for n st n in dom(f^<*p*>) & n+1 in dom(f^<*p*>) holds
   for m,k,i,j st [m,k] in Indices G & [i,j] in Indices G &
     (f^<*p*>)/.n =G*(m,k) & (f^<*p*>)/.(n+1)=G*(i,j)
  holds abs(m-i)+abs(k-j)=1 by A4,A5,GOBOARD1:40;
   now let n such that
A8:  n in dom(f^<*p*>);
  per cases by A8,FINSEQ_1:38;
  suppose
A9:  n in dom f;
   then consider i,j such that
A10:  [i,j] in Indices G and
A11:  f/.n = G*(i,j) by A1,GOBOARD1:def 11;
   take i,j;
   thus [i,j] in Indices G by A10;
   thus (f^<*p*>)/.n = G*(i,j) by A9,A11,GROUP_5:95;
  suppose ex l st l in dom <*p*> & n = (len f) + l;
   then consider l such that
A12:  l in dom <*p*> and
A13:  n = (len f) + l;
    consider i,j such that
A14:  [i,j] in Indices G and
A15:  p = G*(i,j) by A2;
   take i,j;
   thus [i,j] in Indices G by A14;
     1 <= l & l <= len <*p*> by A12,FINSEQ_3:27;
   then 1 <= l & l <= 1 by FINSEQ_1:56;
   then l = 1 by AXIOMS:21;
   then <*p*>/.l = p by FINSEQ_4:25;
   hence (f^<*p*>)/.n = G*(i,j) by A12,A13,A15,GROUP_5:96;
 end;
 hence f^<*p*> is_sequence_on G by A7,GOBOARD1:def 11;
end;

theorem
    i+k < len G & 1 <= j & j < width G & cell(G,i,j) meets cell(G,i+k,j)
    implies k <= 1
proof assume that
A1: i+k < len G and
A2: 1 <= j & j < width G and
A3: cell(G,i,j) meets cell(G,i+k,j) and
A4: k > 1;
   cell(G,i,j) /\ cell(G,i+k,j) <> {} by A3,XBOOLE_0:def 7;
 then consider p such that
A5: p in cell(G,i,j) /\ cell(G,i+k,j) by SUBSET_1:10;
A6: p in cell(G,i,j) & p in cell(G,i+k,j) by A5,XBOOLE_0:def 3;
    i+k >= 1 by A4,NAT_1:37;
  then cell(G,i+k,j) = { |[r',s']| : G*(i+k,1)`1 <= r' & r' <= G*(i+k+1,1)`1
&
                     G*(1,j)`2 <= s' & s' <= G*(1,j+1)`2 }
    by A1,A2,GOBRD11:32;
  then consider r',s' such that
A7: p = |[r',s']| and
A8: G*(i+k,1)`1 <= r' and r' <= G*(i+k+1,1)`1 & G*(1,j)`2 <= s' & s' <=
 G*(1,j+1)`2
   by A6;
A9: 1 < width G by A2,AXIOMS:22;
   i = 0 or i > 0 by NAT_1:19;
then A10: i = 0 or i >= 1+0 by NAT_1:27;
 per cases by A10;
 suppose
A11: i = 0;
  then cell(G,i,j) = {|[r,s]| : r <= G*(1,1)`1 & G*(1,j)`2 <= s & s <= G*
(1,j+1)`2}
   by A2,GOBRD11:26;
  then consider r,s such that
A12: p = |[r,s]| and
A13: r <= G*(1,1)`1 and G*(1,j)`2 <= s & s <= G*(1,j+1)`2 by A6;
A14: k <= len G by A1,NAT_1:37;
    p`1 = r & p`1 = r' by A7,A12,EUCLID:56;
  then G*(k,1)`1 <= G*(1,1)`1 by A8,A11,A13,AXIOMS:22;
  hence contradiction by A4,A9,A14,GOBOARD5:4;
 suppose
A15: i >= 1;
    i < len G by A1,NAT_1:37;
  then cell(G,i,j) =
   {|[r,s]|: G*(i,1)`1 <= r & r <= G*(i+1,1)`1 & G*(1,j)`2 <= s & s <=
 G*(1,j+1)`2}
    by A2,A15,GOBRD11:32;
  then consider r,s such that
A16: p = |[r,s]| and G*(i,1)`1 <= r and
A17: r <= G*(i+1,1)`1 and G*(1,j)`2 <= s & s <= G*(1,j+1)`2 by A6;
A18: 1 <= i+1 & i+1 < k+i by A4,NAT_1:37,REAL_1:53;
    p`1 = r & p`1 = r' by A7,A16,EUCLID:56;
  then G*(i+k,1)`1 <= G*(i+1,1)`1 by A8,A17,AXIOMS:22;
  hence contradiction by A1,A9,A18,GOBOARD5:4;
end;

theorem Th11:
 for C being non empty compact Subset of TOP-REAL 2
   holds C is vertical iff E-bound C <= W-bound C
proof let C be non empty compact Subset of TOP-REAL 2;
A1: E-bound C >= W-bound C by SPRECT_1:23;
     C is vertical iff W-bound C = E-bound C by SPRECT_1:17;
   hence thesis by A1,REAL_1:def 5;
end;

theorem Th12:
 for C being non empty compact Subset of TOP-REAL 2
   holds C is horizontal iff N-bound C <= S-bound C
proof let C be non empty compact Subset of TOP-REAL 2;
A1: N-bound C >= S-bound C by SPRECT_1:24;
     C is horizontal iff N-bound C = S-bound C by SPRECT_1:18;
   hence thesis by A1,REAL_1:def 5;
end;

definition let C be Subset of TOP-REAL 2, n be Nat;
 deffunc f(Nat,Nat) = |[(W-bound C)+(((E-bound C)-(W-bound C))/(2|^n))*($1-2),
                       (S-bound C)+(((N-bound C)-(S-bound C))/(2|^n))*($2-2)]|;
A1: 2|^n + 3 > 0 by NAT_1:19;

 func Gauge (C,n) -> Matrix of TOP-REAL 2 means
:Def1: len it = 2|^n + 3 & len it = width it &
   for i,j st [i,j] in Indices it holds
      it*(i,j) = |[(W-bound C)+(((E-bound C)-(W-bound C))/(2|^n))*(i-2),
                   (S-bound C)+(((N-bound C)-(S-bound C))/(2|^n))*(j-2)]|;
  existence
 proof
   consider M being Matrix of (2|^n + 3) ,(2|^n + 3), the carrier of TOP-REAL 2
   such that
A2:  for i,j st [i,j] in Indices M holds M*(i,j) = f(i,j) from MatrixLambda;
   take M;
   thus len M = 2|^n + 3 by MATRIX_1:def 3;
   hence len M = width M by A1,MATRIX_1:24;
   thus thesis by A2;
 end;
  uniqueness
 proof let M1,M2 be Matrix of TOP-REAL 2 such that
A3:  len M1 = 2|^n + 3 & len M1 = width M1 and
A4:  for i,j st [i,j] in Indices M1 holds M1*(i,j) = f(i,j) and
A5:  len M2 = 2|^n + 3 & len M2 = width M2 and
A6:  for i,j st [i,j] in Indices M2 holds M2*(i,j) = f(i,j);
     now let i,j; assume
A7:  [i,j] in Indices M1;
     M1 is Matrix of (2|^n + 3) ,(2|^n + 3), the carrier of TOP-REAL 2 &
    M2 is Matrix of (2|^n + 3) ,(2|^n + 3), the carrier of TOP-REAL 2
       by A1,A3,A5,MATRIX_1:20;
then A8:  [i,j] in Indices M2 by A7,MATRIX_1:27;
    thus M1*(i,j) = f(i,j) by A4,A7
                 .= M2*(i,j) by A6,A8;
   end;
   hence thesis by A3,A5,MATRIX_1:21;
 end;
end;

definition
 let C be non empty Subset of TOP-REAL 2, n be Nat;
 cluster Gauge (C,n) -> non empty-yielding X_equal-in-line Y_equal-in-column;
  coherence
 proof
  set M = Gauge (C,n);
   len M = 2|^n + 3 & len M = width M by Def1;
  hence M is non empty-yielding by GOBOARD1:def 5;
A1:  Indices M = [:dom M,Seg width M:] by MATRIX_1:def 5;
  thus M is X_equal-in-line
   proof
    let i; assume
A2:   i in dom M;
    set l= Line(M,i), f = X_axis(l);
    let j1,j2 such that
A3:   j1 in dom f and
A4:   j2 in dom f;
      len l = width M by MATRIX_1:def 8;
then A5:   dom l = Seg width M by FINSEQ_1:def 3;
A6:   dom f = dom l by SPRECT_2:19;
then A7:   l/.j1 = l.j1 by A3,FINSEQ_4:def 4
             .= M*(i,j1) by A3,A5,A6,MATRIX_1:def 8;
A8:   [i,j1] in Indices M by A1,A2,A3,A5,A6,ZFMISC_1:106;
A9:   l/.j2 = l.j2 by A4,A6,FINSEQ_4:def 4
             .= M*(i,j2) by A4,A5,A6,MATRIX_1:def 8;
A10:   [i,j2] in Indices M by A1,A2,A4,A5,A6,ZFMISC_1:106;
    set x = (W-bound C)+(((E-bound C)-(W-bound C))/(2|^n))*(i-2);
    set d = ((N-bound C)-(S-bound C))/(2|^n);
   thus f.j1 = (l/.j1)`1 by A3,GOBOARD1:def 3
            .= |[x,(S-bound C)+d*(j1-2)]|`1 by A7,A8,Def1
            .= x by EUCLID:56
            .= |[x,(S-bound C)+d*(j2-2)]|`1 by EUCLID:56
            .= (l/.j2)`1 by A9,A10,Def1
            .= f.j2 by A4,GOBOARD1:def 3;
   end;
  thus M is Y_equal-in-column
   proof
    let j; assume
A11:   j in Seg width M;
    set c = Col(M,j), f = Y_axis(c);
    let i1,i2 such that
A12:   i1 in dom f and
A13:   i2 in dom f;
      len c = len M by MATRIX_1:def 9;
then A14:   dom c = dom M by FINSEQ_3:31;
A15:   dom f = dom c by SPRECT_2:20;
then A16:   c/.i1 = c.i1 by A12,FINSEQ_4:def 4
             .= M*(i1,j) by A12,A14,A15,MATRIX_1:def 9;
A17:   [i1,j] in Indices M by A1,A11,A12,A14,A15,ZFMISC_1:106;
A18:   c/.i2 = c.i2 by A13,A15,FINSEQ_4:def 4
             .= M*(i2,j) by A13,A14,A15,MATRIX_1:def 9;
A19:   [i2,j] in Indices M by A1,A11,A13,A14,A15,ZFMISC_1:106;
    set y = (S-bound C)+(((N-bound C)-(S-bound C))/(2|^n))*(j-2);
    set d = ((E-bound C)-(W-bound C))/(2|^n);
    thus f.i1 = (c/.i1)`2 by A12,GOBOARD1:def 4
             .= |[(W-bound C)+d*(i1-2),y]|`2 by A16,A17,Def1
             .= y by EUCLID:56
             .= |[(W-bound C)+d*(i2-2),y]|`2 by EUCLID:56
             .= (c/.i2)`2 by A18,A19,Def1
             .= f.i2 by A13,GOBOARD1:def 4;
   end;
 end;
end;

definition
  let C be compact non vertical non horizontal non empty Subset of TOP-REAL 2,
      n;
 cluster Gauge (C,n) -> Y_increasing-in-line X_increasing-in-column;
  coherence
 proof
  set M = Gauge (C,n);
A1:  Indices M = [:dom M,Seg width M:] by MATRIX_1:def 5;
  thus M is Y_increasing-in-line
   proof
    let i; assume
A2:    i in dom M;
    set l = Line(M,i), f = Y_axis(l);
    let j1,j2 such that
A3:   j1 in dom f and
A4:   j2 in dom f and
A5:   j1 < j2;
      len l = width M by MATRIX_1:def 8;
then A6:   dom l = Seg width M by FINSEQ_1:def 3;
A7:   dom f = dom l by SPRECT_2:20;
then A8:   l/.j1 = l.j1 by A3,FINSEQ_4:def 4
             .= M*(i,j1) by A3,A6,A7,MATRIX_1:def 8;
A9:   [i,j1] in Indices M by A1,A2,A3,A6,A7,ZFMISC_1:106;
A10:   l/.j2 = l.j2 by A4,A7,FINSEQ_4:def 4
             .= M*(i,j2) by A4,A6,A7,MATRIX_1:def 8;
A11:   [i,j2] in Indices M by A1,A2,A4,A6,A7,ZFMISC_1:106;
    set x = (W-bound C)+(((E-bound C)-(W-bound C))/(2|^n))*(i-2);
    set d = ((N-bound C)-(S-bound C))/(2|^n);
A12:   f.j1 = (l/.j1)`2 by A3,GOBOARD1:def 4
          .= |[x,(S-bound C)+d*(j1-2)]|`2 by A8,A9,Def1
          .= (S-bound C)+d*(j1-2) by EUCLID:56;
A13:   f.j2 = (l/.j2)`2 by A4,GOBOARD1:def 4
          .= |[x,(S-bound C)+d*(j2-2)]|`2 by A10,A11,Def1
          .= (S-bound C)+d*(j2-2) by EUCLID:56;
      N-bound C > S-bound C by Th12;
    then (N-bound C)-(S-bound C) > 0 & (2|^n) > 0 by HEINE:5,SQUARE_1:11;
then A14:    d > 0 by REAL_2:127;
      j1-2 < j2 -2 by A5,REAL_1:54;
    then d*(j1-2) < d*(j2-2) by A14,REAL_1:70;
    hence f.j1 < f.j2 by A12,A13,REAL_1:67;
   end;
  let j; assume
A15:   j in Seg width M;
  set c = Col(M,j), f = X_axis(c);
  let i1,i2 such that
A16:   i1 in dom f and
A17:   i2 in dom f and
A18:   i1 < i2;
     len c = len M by MATRIX_1:def 9;
then A19:   dom c = dom M by FINSEQ_3:31;
A20:   dom f = dom c by SPRECT_2:19;
then A21:   c/.i1 = c.i1 by A16,FINSEQ_4:def 4
             .= M*(i1,j) by A16,A19,A20,MATRIX_1:def 9;
A22:   [i1,j] in Indices M by A1,A15,A16,A19,A20,ZFMISC_1:106;
A23:   c/.i2 = c.i2 by A17,A20,FINSEQ_4:def 4
             .= M*(i2,j) by A17,A19,A20,MATRIX_1:def 9;
A24:   [i2,j] in Indices M by A1,A15,A17,A19,A20,ZFMISC_1:106;
    set y = (S-bound C)+(((N-bound C)-(S-bound C))/(2|^n))*(j-2);
    set d = ((E-bound C)-(W-bound C))/(2|^n);
A25:   f.i1 = (c/.i1)`1 by A16,GOBOARD1:def 3
          .= |[(W-bound C)+d*(i1-2),y]|`1 by A21,A22,Def1
          .= (W-bound C)+d*(i1-2) by EUCLID:56;
A26:   f.i2 = (c/.i2)`1 by A17,GOBOARD1:def 3
          .= |[(W-bound C)+d*(i2-2),y]|`1 by A23,A24,Def1
          .= (W-bound C)+d*(i2-2) by EUCLID:56;
      E-bound C > W-bound C by Th11;
    then (E-bound C)-(W-bound C) > 0 & (2|^n) > 0 by HEINE:5,SQUARE_1:11;
then A27:   d > 0 by REAL_2:127;
      i1-2 < i2 -2 by A18,REAL_1:54;
    then d*(i1-2) < d*(i2-2) by A27,REAL_1:70;
    hence f.i1 < f.i2 by A25,A26,REAL_1:67;
 end;
end;

reserve T for non empty Subset of TOP-REAL 2;

theorem Th13:
 len Gauge(T,n) >= 4
proof set G = Gauge(T,n);
A1:  len G = 2|^n + 3 by Def1;
    2|^n >= n + 1 by HEINE:7;
  then len G >= n + 1 + 3 by A1,AXIOMS:24;
  then len G >= n + (3 + 1) & n+4 >= 4 by NAT_1:37,XCMPLX_1:1;
  hence len G >= 4 by AXIOMS:22;
end;

theorem
    1 <= j & j <= len Gauge(T,n) implies Gauge(T,n)*(2,j)`1 = W-bound T
proof set G = Gauge(T,n);
  set W = W-bound T, S = S-bound T, E = E-bound T, N = N-bound T;
  assume
A1:  1 <= j & j <= len Gauge(T,n);
A2:  len G = 2|^n + 3 & len G = width G by Def1;
    len G >= 4 by Th13;
  then 2 <= len G by AXIOMS:22;
  then [2,j] in Indices G by A1,A2,GOBOARD7:10;
  then G*(2,j) = |[W+((E-W)/(2|^n))*(2-2), S+(N-S)/(2|^n)*(j-2)]| by Def1;
  hence G*(2,j)`1 = W-bound T by EUCLID:56;
end;

theorem
    1 <= j & j <= len Gauge(T,n) implies
    Gauge(T,n)*(len Gauge(T,n)-'1,j)`1 = E-bound T
proof set G = Gauge(T,n);
  set W = W-bound T, S = S-bound T, E = E-bound T, N = N-bound T;
  assume
A1:  1 <= j & j <= len Gauge(T,n);
A2:  len G = 2|^n + 3 & len G = width G by Def1;
    len G >= 4 by Th13;
then A3:  1 < len G by AXIOMS:22;
then A4:  1 <= (len G)-'1 by JORDAN3:12;
A5:  (len G)-'1-2 = (len G)-1-2 by A3,SCMFSA_7:3
                 .= (len G)-(1+2) by XCMPLX_1:36
                 .= 2|^n by A2,XCMPLX_1:26;
A6:  2|^n > 0 by HEINE:5;
    (len G)-'1 <= len G by GOBOARD9:2;
  then [(len G)-'1,j] in Indices G by A1,A2,A4,GOBOARD7:10;
  then G*((len G)-'1,j)
    = |[W+((E-W)/(2|^n))*((len G)-'1-2), S+((N-S)/(2|^n))*(j-2)]| by Def1;
  hence G*((len G)-'1,j)`1 = W+((E-W)/(2|^n))*(2|^n) by A5,EUCLID:56
                          .= W+(E-W) by A6,XCMPLX_1:88
                          .= E-bound T by XCMPLX_1:27;
end;

theorem
    1 <= i & i <= len Gauge(T,n) implies Gauge(T,n)*(i,2)`2 = S-bound T
proof set G = Gauge(T,n);
  set W = W-bound T, S = S-bound T, E = E-bound T, N = N-bound T;
  assume
A1:  1 <= i & i <= len Gauge(T,n);
A2:  len G = 2|^n + 3 & len G = width G by Def1;
    len G >= 4 by Th13;
  then 2 <= len G by AXIOMS:22;
  then [i,2] in Indices G by A1,A2,GOBOARD7:10;
  then G*(i,2) = |[W+((E-W)/(2|^n))*(i-2), S+((N-S)/(2|^n))*(2-2)]| by Def1;
  hence G*(i,2)`2 = S-bound T by EUCLID:56;
end;

theorem
    1 <= i & i <= len Gauge(T,n) implies
    Gauge(T,n)*(i,len Gauge(T,n)-'1)`2 = N-bound T
proof set G = Gauge(T,n);
  set W = W-bound T, S = S-bound T, E = E-bound T, N = N-bound T;
  assume
A1:  1 <= i & i <= len Gauge(T,n);
A2:  len G = 2|^n + 3 & len G = width G by Def1;
    len G >= 4 by Th13;
then A3:  1 < len G by AXIOMS:22;
then A4:  1 <= (len G)-'1 by JORDAN3:12;
A5:  (len G)-'1-2 = (len G)-1-2 by A3,SCMFSA_7:3
                 .= (len G)-(1+2) by XCMPLX_1:36
                 .= 2|^n by A2,XCMPLX_1:26;
A6:  2|^n > 0 by HEINE:5;
    (len G)-'1 <= len G by GOBOARD9:2;
  then [i,(len G)-'1] in Indices G by A1,A2,A4,GOBOARD7:10;
  then G*(i,(len G)-'1)
    = |[W+((E-W)/(2|^n))*(i-2), S+((N-S)/(2|^n))*((len G)-'1-2)]| by Def1;
  hence G*(i,(len G)-'1)`2 = S+((N-S)/(2|^n))*(2|^n) by A5,EUCLID:56
                          .= S+(N-S) by A6,XCMPLX_1:88
                          .= N-bound T by XCMPLX_1:27;
end;

reserve C for
   compact non vertical non horizontal non empty Subset of TOP-REAL 2;

theorem
    i <= len Gauge(C,n) implies cell(Gauge(C,n),i,len Gauge(C,n)) misses C
proof set G = Gauge(C,n);
 assume
A1:  i <= len G;
A2:  len G = 2|^n + (1+2) & len G = width G by Def1;
 assume cell(G,i,len G) /\ C <> {};
 then consider p such that
A3: p in cell(G,i,len G) /\ C by SUBSET_1:10;
A4: p in cell(G,i,len G) & p in C by A3,XBOOLE_0:def 3;
   4 <= len G by Th13;
then A5: 1 <= len G by AXIOMS:22;
  set W = W-bound C, S = S-bound C, E = E-bound C, N = N-bound C;
  set NS = (N-S)/(2|^n);
    [1,width G] in Indices G by A2,A5,GOBOARD7:10;
  then G*(1,width G) = |[W+((E-W)/(2|^n))*(1-2), S+NS*((width G)-2)]| by Def1;
  then A6:  G*(1,width G)`2 = S+NS*((width G)-2) by EUCLID:56;
A7:  2|^n > 0 by HEINE:5;
    N > S by Th12;
  then N-S > 0 by SQUARE_1:11;
then A8:  NS > 0 by A7,REAL_2:127;
     (width G)-2 = 2|^n + 1 + 2 - 2 by A2,XCMPLX_1:1
              .= 2|^n + 1 by XCMPLX_1:26;
   then NS*((width G)-2) = NS*(2|^n) + NS*1 by XCMPLX_1:8
                        .= N-S+NS by A7,XCMPLX_1:88;
   then G*(1,width G)`2 = S+(N-S)+NS by A6,XCMPLX_1:1
                       .= N + NS by XCMPLX_1:27;
then A9:  G*(1,width G)`2 > N by A8,REAL_1:69;
    i = 0 or i > 0 by NAT_1:19;
then A10: i = 0 or i >= 1+0 by NAT_1:27;
 per cases by A1,A10,REAL_1:def 5;
 suppose i = 0;
  then cell(G,i,width G) = { |[r,s]| : r <= G*(1,1)`1 & G*(1,width G)`2 <= s }
   by GOBRD11:25;
  then consider r,s such that
A11: p = |[r,s]| and
A12: r <= G*(1,1)`1 & G*(1,width G)`2 <= s by A2,A4;
    p`2 = s by A11,EUCLID:56;
  then N < p`2 & p`2 <= N by A4,A9,A12,AXIOMS:22,PSCOMP_1:71;
  hence contradiction;
 suppose i = len G;
   then cell(G,i,width G)={|[r,s]| : G*(len G,1)`1 <= r & G*(1,width G)`2 <= s
}
     by GOBRD11:28;
  then consider r,s such that
A13: p = |[r,s]| and
A14: G*(len G,1)`1 <= r & G*(1,width G)`2 <= s by A2,A4;
    p`2 = s by A13,EUCLID:56;
  then N < p`2 & p`2 <= N by A4,A9,A14,AXIOMS:22,PSCOMP_1:71;
  hence contradiction;
 suppose 1 <= i & i < len G;
  then cell(G,i,width G)
          = {|[r,s]|: G*(i,1)`1 <= r & r <= G*(i+1,1)`1 & G*
(1,width G)`2 <= s}
  by GOBRD11:31;
  then consider r,s such that
A15: p = |[r,s]| and
A16: G*(i,1)`1 <= r & r <= G*(i+1,1)`1 & G*(1,width G)`2 <= s by A2,A4;
    p`2 = s by A15,EUCLID:56;
  then N < p`2 & p`2 <= N by A4,A9,A16,AXIOMS:22,PSCOMP_1:71;
  hence contradiction;
end;

theorem
    j <= len Gauge(C,n) implies cell(Gauge(C,n),len Gauge(C,n),j) misses C
proof set G = Gauge(C,n);
 assume
A1:  j <= len G;
A2:  len G = 2|^n + (1+2) & len G = width G by Def1;
 assume cell(G,len G,j) /\ C <> {};
 then consider p such that
A3: p in cell(G,len G,j) /\ C by SUBSET_1:10;
A4: p in cell(G,len G,j) & p in C by A3,XBOOLE_0:def 3;
   4 <= len G by Th13;
then A5: 1 <= len G by AXIOMS:22;
  set W = W-bound C, S = S-bound C, E = E-bound C, N = N-bound C;
  set EW = (E-W)/(2|^n);
    [len G,1] in Indices G by A2,A5,GOBOARD7:10;
  then G*(len G,1) = |[W+EW*((len G)-2), S+((N-S)/(2|^n))*(1-2)]| by Def1;
  then A6:  G*(len G,1)`1 = W+EW*((len G)-2) by EUCLID:56;
A7:  2|^n > 0 by HEINE:5;
    E > W by Th11;
  then E-W > 0 by SQUARE_1:11;
then A8:  EW > 0 by A7,REAL_2:127;
     (len G)-2 = 2|^n + 1 + 2 - 2 by A2,XCMPLX_1:1
            .= 2|^n + 1 by XCMPLX_1:26;
   then EW*((len G)-2) = EW*(2|^n) + EW*1 by XCMPLX_1:8
                      .= E-W+EW by A7,XCMPLX_1:88;
   then G*(len G,1)`1 = W+(E-W)+EW by A6,XCMPLX_1:1
                       .= E + EW by XCMPLX_1:27;
then A9:  G*(len G,1)`1 > E by A8,REAL_1:69;
    j = 0 or j > 0 by NAT_1:19;
then A10: j = 0 or j >= 1+0 by NAT_1:27;
 per cases by A1,A10,REAL_1:def 5;
 suppose j = 0;
  then cell(G,len G,j) = {|[r,s]| : G*(len G,1)`1 <= r & s <= G*(1,1)`2}
    by GOBRD11:27;
  then consider r,s such that
A11: p = |[r,s]| and
A12: G*(len G,1)`1 <= r & s <= G*(1,1)`2 by A4;
    p`1 = r by A11,EUCLID:56;
  then E < p`1 & p`1 <= E by A4,A9,A12,AXIOMS:22,PSCOMP_1:71;
  hence contradiction;
 suppose j = len G;
   then cell(G,len G,j)={|[r,s]| : G*(len G,1)`1 <= r & G*(1,width G)`2 <= s}
     by A2,GOBRD11:28;
  then consider r,s such that
A13: p = |[r,s]| and
A14: G*(len G,1)`1 <= r & G*(1,width G)`2 <= s by A4;
    p`1 = r by A13,EUCLID:56;
  then E < p`1 & p`1 <= E by A4,A9,A14,AXIOMS:22,PSCOMP_1:71;
  hence contradiction;
 suppose 1 <= j & j < len G;
  then cell(G,len G,j)
   = { |[r,s]| : G*(len G,1)`1 <= r & G*(1,j)`2 <= s & s <= G*(1,j+1)`2 }
    by A2,GOBRD11:29;
  then consider r,s such that
A15: p = |[r,s]| and
A16: G*(len G,1)`1 <= r & G*(1,j)`2 <= s & s <= G*(1,j+1)`2 by A4;
    p`1 = r by A15,EUCLID:56;
  then E < p`1 & p`1 <= E by A4,A9,A16,AXIOMS:22,PSCOMP_1:71;
  hence contradiction;
end;

theorem
    i <= len Gauge(C,n) implies cell(Gauge(C,n),i,0) misses C
proof set G = Gauge(C,n);
 assume
A1:  i <= len G;
A2:  len G = 2|^n + (1+2) & len G = width G by Def1;
 assume cell(G,i,0) /\ C <> {};
 then consider p such that
A3: p in cell(G,i,0) /\ C by SUBSET_1:10;
A4: p in cell(G,i,0) & p in C by A3,XBOOLE_0:def 3;
   4 <= len G by Th13;
then A5: 1 <= len G by AXIOMS:22;
  set W = W-bound C, S = S-bound C, E = E-bound C, N = N-bound C;
  set NS = (N-S)/(2|^n);
    [1,1] in Indices G by A2,A5,GOBOARD7:10;
  then G*(1,1) = |[W+((E-W)/(2|^n))*(1-2), S+NS*(1-2)]| by Def1;
then A6:  G*(1,1)`2 = S+NS*(-1) by EUCLID:56;
A7:  2|^n > 0 by HEINE:5;
    N > S by Th12;
  then N-S > 0 by SQUARE_1:11;
  then NS > 0 by A7,REAL_2:127;
  then NS*(-1) < 0 * (-1) by REAL_1:71;
then A8:  G*(1,1)`2 < S+0 by A6,REAL_1:53;
    i = 0 or i > 0 by NAT_1:19;
then A9: i = 0 or i >= 1+0 by NAT_1:27;
 per cases by A1,A9,REAL_1:def 5;
 suppose i = 0;
  then cell(G,i,0) ={ |[r,s]| : r <= G*(1,1)`1 & s <= G*(1,1)`2 }
   by GOBRD11:24;
  then consider r,s such that
A10: p = |[r,s]| and
A11: r <= G*(1,1)`1 & s <= G*(1,1)`2 by A4;
    p`2 = s by A10,EUCLID:56;
  then S > p`2 & p`2 >= S by A4,A8,A11,AXIOMS:22,PSCOMP_1:71;
  hence contradiction;
 suppose i = len G;
   then cell(G,i,0)={ |[r,s]| : G*(len G,1)`1 <= r & s <= G*(1,1)`2 }
     by GOBRD11:27;
  then consider r,s such that
A12: p = |[r,s]| and
A13: G*(len G,1)`1 <= r & s <= G*(1,1)`2 by A4;
    p`2 = s by A12,EUCLID:56;
  then S > p`2 & p`2 >= S by A4,A8,A13,AXIOMS:22,PSCOMP_1:71;
  hence contradiction;
 suppose 1 <= i & i < len G;
  then cell(G,i,0) = { |[r,s]|: G*(i,1)`1 <= r & r <= G*(i+1,1)`1 & s <= G*
(1,1)`2 }
    by GOBRD11:30;
  then consider r,s such that
A14: p = |[r,s]| and
A15: G*(i,1)`1 <= r & r <= G*(i+1,1)`1 & s <= G*(1,1)`2 by A4;
    p`2 = s by A14,EUCLID:56;
  then S > p`2 & p`2 >= S by A4,A8,A15,AXIOMS:22,PSCOMP_1:71;
  hence contradiction;
end;

theorem
    j <= len Gauge(C,n) implies cell(Gauge(C,n),0,j) misses C
proof set G = Gauge(C,n);
 assume
A1:  j <= len G;
A2:  len G = 2|^n + (1+2) & len G = width G by Def1;
 assume cell(G,0,j) /\ C <> {};
 then consider p such that
A3: p in cell(G,0,j) /\ C by SUBSET_1:10;
A4: p in cell(G,0,j) & p in C by A3,XBOOLE_0:def 3;
   4 <= len G by Th13;
then A5: 1 <= len G by AXIOMS:22;
  set W = W-bound C, S = S-bound C, E = E-bound C, N = N-bound C;
  set EW = (E-W)/(2|^n);
    [1,1] in Indices G by A2,A5,GOBOARD7:10;
  then G*(1,1) = |[W+EW*(1-2), S+((N-S)/(2|^n))*(1-2)]| by Def1;
then A6:  G*(1,1)`1 = W+EW*(-1) by EUCLID:56;
A7:  2|^n > 0 by HEINE:5;
    E > W by Th11;
  then E-W > 0 by SQUARE_1:11;
  then EW > 0 by A7,REAL_2:127;
  then EW*(-1) < 0 * (-1) by REAL_1:71;
then A8:  G*(1,1)`1 < W+0 by A6,REAL_1:53;
    j = 0 or j > 0 by NAT_1:19;
then A9: j = 0 or j >= 1+0 by NAT_1:27;
 per cases by A1,A9,REAL_1:def 5;
 suppose j = 0;
  then cell(G,0,j) = { |[r,s]| : r <= G*(1,1)`1 & s <= G*(1,1)`2 }
   by GOBRD11:24;
  then consider r,s such that
A10: p = |[r,s]| and
A11: r <= G*(1,1)`1 & s <= G*(1,1)`2 by A4;
    p`1 = r by A10,EUCLID:56;
  then W > p`1 & p`1 >= W by A4,A8,A11,AXIOMS:22,PSCOMP_1:71;
  hence contradiction;
 suppose j = len G;
   then cell(G,0,j)={ |[r,s]| : r <= G*(1,1)`1 & G*(1,width G)`2 <= s }
     by A2,GOBRD11:25;
  then consider r,s such that
A12: p = |[r,s]| and
A13: r <= G*(1,1)`1 & G*(1,width G)`2 <= s by A4;
    p`1 = r by A12,EUCLID:56;
  then W > p`1 & p`1 >= W by A4,A8,A13,AXIOMS:22,PSCOMP_1:71;
  hence contradiction;
 suppose 1 <= j & j < len G;
  then cell(G,0,j) = { |[r,s]| : r <= G*(1,1)`1 & G*(1,j)`2 <= s & s <=
 G*(1,j+1)`2 }
    by A2,GOBRD11:26;
  then consider r,s such that
A14: p = |[r,s]| and
A15: r <= G*(1,1)`1 & G*(1,j)`2 <= s & s <= G*(1,j+1)`2 by A4;
    p`1 = r by A14,EUCLID:56;
  then W > p`1 & p`1 >= W by A4,A8,A15,AXIOMS:22,PSCOMP_1:71;
  hence contradiction;
end;

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